ZIMMERMANN TELEGRAM. The intercepted and decrypted mes-
sage that hastened the entry of the United States into World War I, the
Zimmermann Telegram can be traced to Arthur von Kemnitz, an East
Asia expert in the German Foreign Office. His proposal—to provide
financial support to the Mexican government so it could reconquer
lost territory in Texas, New Mexico, and Arizona—was endorsed by
Foreign Minister Arthur Zimmermann, who then advised the Ger-
man ambassador in Mexico City, Heinrich von Eckhardt, to make
the offer of an alliance. However remote the prospects of success,
Zimmermann calculated that a large-scale military entanglement in
Mexico would keep the United States at bay and prevent further arms
shipments to Europe.
Because of the urgency of the matter—unrestricted submarine war-
fare was to be announced on 1 February 1917—three copies of Zim-
mermann’s encrypted confidential note were sent on 16 January: one
by radio from Nauen (Brandenburg) to Sayville, Long Island; a second
via the Swedish transatlantic cable from Stockholm; and a third on the
American cable from the U.S. embassy in Berlin. Its first recipient was
the German ambassador to the United States, Johann Heinrich Count
von Bernstorff, who then cabled the message to Mexico City.
Unknown to the Germans, however, was the interception of the
telegram by the British and its decryption by the naval intelligence
unit known as Room 40. Relying on copies of various German code-
books obtained earlier, it also decoded Zimmermann’s second tele-
gram, which had added Japan to the proposed alliance. To cover their
tracks—and keep the Germans convinced of the inviolability of their
codes—the British secured a copy of the first telegram that had been
received by the Mexican Telegraph Office. After the document was
passed to the U.S. ambassador to Great Britain, President Woodrow
Wilson released it on 1 March to the American press, which was al-
ready filled with dramatic stories of German sabotage and submarine
warfare. Zimmermann’s inexplicable but candid acknowledgment as
the author of the telegram removed any doubts about its authentic-
ity. On 2 April, his hope for a negotiated peace dashed by the public
clamor, Wilson announced to Congress the end of the country’s
policy of neutrality. See also MAGDEBURG.
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